351 research outputs found

    Argue but obey? Questioning Kant’s enlightenment

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    Este trabajo enfoca la célebre distinción de Kant entre el uso privado y público de la razón, tal y como se presenta en su opúsculo Respuesta a la pregunta ¿Qué es la Ilustración? Tras analizar la distinción de Kant, le dirijo diez críticas específicas, concluyendo que su apoyo a la máxima de Friedrich “Razonad, pero obedeced”, es un mal consejo.This essay focuses on Kant’s famous distinction between the public and private use of reason, as presented in his short essay An Answer to the Question, What is Enlightenment? After analyzing Kant’s distinction, I present ten specific criticisms of it, concluding that his endorsement of Friedrich’s maxim, “Argue but obey” is poor advice

    El Kant de Foucault

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    Muchos kantianos se mostraron asombrados, muy asombrados, cuando supieron que Michel Foucault, satisfaciendo parte de las exigencias de su doctorado en filosofía, no sólo había traducido, sino también escrito un detallado ensayo interpretativo de la Antropología en sentido pragmático de Kant

    Kantian anthropology: a science like no other

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    In this essay I begin by examining Kant’s criteria for “proper science” as presented in the Preface to his Metaphysical Foundations of Science, and then ask whether Kantian anthropology can possibly qualify as a proper science according to these demanding criteria. I defend a qualified ‘yes’ answer to this question, while also drawing attention to several less tidy aspects of his anthropology project that are difficult to fit onto the Procrustean bed of science

    High-energy environment of super-Earth 55 Cnc e I: Far-UV chromospheric variability as a possible tracer of planet-induced coronal rain

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    The irradiation of close-in planets by their star influences their evolution and might be responsible for a population of ultra-short period planets eroded to their bare core. In orbit around a bright, nearby G-type star, the super-Earth 55 Cnc e offers the possibility to address these issues through UV transit observations. We used the Hubble Space Telescope to observe the transit in the FUV over 3 epochs in Apr. 2016, Jan. 2017, and Feb. 2017. These observations reveal significant short- and long-term variability in 55 Cnc chromospheric emission lines. In the last 2 epochs, we detected a larger flux in the C III, Si III, and Si IV lines after the planet passed the approaching quadrature, followed by a flux decrease in the Si IV doublet. In the second epoch these variations are contemporaneous with flux decreases in the Si II and C II doublet. All epochs show flux decreases in the N V doublet as well, albeit at different orbital phases. These flux decreases are consistent with absorption from optically thin clouds of gas, are mostly localized at low and redshifted radial velocities in the star rest frame, and occur preferentially before and during the transit. These 3 points make it unlikely that the variations are purely stellar, yet we show that the occulting material is also unlikely to originate from the planet. We tentatively propose that the motion of 55 Cnc e at the fringes of the stellar corona leads to the formation of a cool coronal rain. The inhomogeneity and temporal evolution of the stellar corona would be responsible for the differences between the visits. Additional variations are detected in the C II doublet in the first epoch and in the O I triplet in all epochs with a different behavior that points toward intrinsic stellar variability. Further observations at FUV wavelengths are required to disentangle between star-planet interactions and the activity of the starComment: 22 pages, 20 figures, accepted for publication in A&

    Precision study of 6p 2Pj - 8s 2S1/2 relative transition matrix elements in atomic Cs

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    A combined experimental and theoretical study of transition matrix elements of the 6p 2Pj - 8s 2S1/2 transition in atomic Cs is reported. Measurements of the polarization-dependent two-photon excitation spectrum associated with the transition were made in an approximately 200 cm-1 range on the low frequency side of the 6s 2S1/2 - 6p 2P3/2 resonance. The measurements depend parametrically on the relative transition matrix elements, but also are sensitive to far-off-resonance 6s 2S1/2 - np 2Pj - 8s 2S1/2 transitions. In the past, this dependence has yielded a generalized sum rule, the value of which is dependent on sums of relative two-photon transition matrix elements. In the present case, best available determinations from other experiments are combined with theoretical matrix elements to extract the ratio of transition matrix elements for the 6p 2Pj - 8s 2S1/2 (j = 1/2,3/2) transition. The resulting experimental value of 1.423(2) is in excellent agreement with the theoretical value, calculated using a relativistic all-order method, of 1.425(2)

    Potential influence of selection criteria on the demographic composition of students in an Australian medical school

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    <p>Abstract</p> <p>Background</p> <p>Prior to 1999 students entering our MBBS course were selected on academic performance alone. We have now evaluated the impact on the demographics of subsequent cohorts of our standard entry students (those entering directly from high school) of the addition to the selection process of an aptitude test (UMAT), a highly structured interview and a rural incentive program.</p> <p>Methods</p> <p>Students entering from 1985 to 1998, selected on academic performance alone (N = 1402), were compared to those from 1999 to 2011, selected on the basis of a combination of academic performance, interview score, and UMAT score together with the progressive introduction of a rural special entry pathway (N = 1437).</p> <p>Results</p> <p>Males decreased from 57% to 45% of the cohort, students of NE or SE Asian origin decreased from 30% to 13%, students born in Oceania increased from 52% to 69%, students of rural origin from 5% to 21% and those from independent high schools from 56% to 66%. The proportion of students from high schools with relative socio-educational disadvantage remained unchanged at approximately 10%. The changes reflect in part increasing numbers of female and independent high school applicants and the increasing rural quota. However, they were also associated with higher interview scores in females vs males and lower interview scores in those of NE and SE Asian origin compared to those born in Oceania or the UK. Total UMAT scores were unrelated to gender or region of origin.</p> <p>Conclusions</p> <p>The revised selection processes had no impact on student representation from schools with relative socio-educational disadvantage. However, the introduction of special entry quotas for students of rural origin and a structured interview, but not an aptitude test, were associated with a change in gender balance and ethnicity of students in an Australian undergraduate MBBS course.</p

    Mapping Exoplanets

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    The varied surfaces and atmospheres of planets make them interesting places to live, explore, and study from afar. Unfortunately, the great distance to exoplanets makes it impossible to resolve their disk with current or near-term technology. It is still possible, however, to deduce spatial inhomogeneities in exoplanets provided that different regions are visible at different times---this can be due to rotation, orbital motion, and occultations by a star, planet, or moon. Astronomers have so far constructed maps of thermal emission and albedo for short period giant planets. These maps constrain atmospheric dynamics and cloud patterns in exotic atmospheres. In the future, exo-cartography could yield surface maps of terrestrial planets, hinting at the geophysical and geochemical processes that shape them.Comment: Updated chapter for Handbook of Exoplanets, eds. Deeg & Belmonte. 17 pages, including 6 figures and 4 pages of reference

    Global Climate and Atmospheric Composition of the Ultra-Hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations

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    We present thermal phase curve measurements for the hot Jupiter WASP-103b observed with Hubble/WFC3 and Spitzer/IRAC. The phase curves have large amplitudes and negligible hotspot offsets, indicative of poor heat redistribution to the nightside. We fit the phase variation with a range of climate maps and find that a spherical harmonics model generally provides the best fit. The phase-resolved spectra are consistent with blackbodies in the WFC3 bandpass, with brightness temperatures ranging from 1880±401880\pm40 K on the nightside to 2930±402930 \pm 40 K on the dayside. The dayside spectrum has a significantly higher brightness temperature in the Spitzer bands, likely due to CO emission and a thermal inversion. The inversion is not present on the nightside. We retrieved the atmospheric composition and found the composition is moderately metal-enriched ([M/H]=2313+29×\mathrm{[M/H]} = 23^{+29}_{-13}\times solar) and the carbon-to-oxygen ratio is below 0.9 at 3σ3\,\sigma confidence. In contrast to cooler hot Jupiters, we do not detect spectral features from water, which we attribute to partial H2_2O dissociation. We compare the phase curves to 3D general circulation models and find magnetic drag effects are needed to match the data. We also compare the WASP-103b spectra to brown dwarfs and young directly imaged companions and find these objects have significantly larger water features, indicating that surface gravity and irradiation environment play an important role in shaping the spectra of hot Jupiters. These results highlight the 3D structure of exoplanet atmospheres and illustrate the importance of phase curve observations for understanding their complex chemistry and physics.Comment: 25 pages, 17 figures, 7 tables; accepted to A
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